1. Technical Field
The present invention relates to a liquid ejecting apparatus having a function of agitating a liquid.
2. Related Art
As ink to be used in a liquid ejecting apparatus, for example, a printer device, there is known ink using a color component which is not dissolved by a solvent or is nearly insoluble in the solvent. For example, pigment-based ink contains fine particles of pigment which are a color component and are dispersed in a solvent such as water or petroleum solvent, and the pigment is likely to be settled down. For example, specific gravity of white pigment is approximately 4 and specific gravity of metallic pigment is approximately 2 to 3, but specific gravity of the solvent is less than 1. Because of a difference in the specific gravity between the pigment and the solvent, the pigment is easily separated from the solvent and is precipitated. Also, in the case of the ink using insoluble or hardly-soluble dye as a color component, the dye is likely to be precipitated. If the color component is precipitated, shading occurs in the ink, so that ink of uniform concentration is not fed to the head. There is a problem that a dense portion of the ink does not fall in drops from a nozzle of the head, so that the nozzle is likely clogged, or brightness of a dot is changed.
It is known that the ink is moved and agitated to prevent sedimentation of the color component. For example, a technique of providing a first ink containing unit (i.e., an ink tank) and a second ink containing unit and reciprocating the ink between two ink containing units is known (e.g., JP-A-9-327929, WO95/31335, and JP-A-9-234886).
In the above-mentioned publications, however, the ink is moved between two ink containing units due to difference in height, that is, a water head difference, between a liquid level of the ink filled in the first ink containing unit and a liquid level of the ink filled in the second ink containing unit. In other words, only a portion of the ink reciprocates between two ink containing units, and thus only the portion is agitated. For this reason, the ink remaining in the ink containing units is insufficiently agitated, and thus it does not prevent sedimentation of the color component of the ink in the ink containing units.